Method for judging type of direct-current power supply

Abstract

The invention provides a method for judging the type of a direct-current power supply, and the direct-current power supply is configured to be connected to an outdoor power supply so as to charge the outdoor power supply. The method comprises the following steps: step 1, acquiring a first equivalent resistance and a second equivalent resistance of the direct-current power supply corresponding to two different equivalent load resistances of the outdoor power supply respectively; 2, calculating the ratio of the first equivalent resistance to the second equivalent resistance; 3, if the ratio is within a preset threshold range, judging that the direct-current power supply is a vehicle-mounted battery; otherwise, judging that the direct-current power supply is a solar panel.

Description

Technical Field

[0001] The invention belongs to the field of electric power supply, and in particular relates to a method for determining the type of direct current power supply. Background Art

[0002] An outdoor power supply is a multifunctional outdoor power supply with a built-in lithium-ion battery that can store its own electrical energy. It is also called a portable AC / DC power supply. An outdoor power supply is equivalent to a small portable charging station. It has the characteristics of light weight, high capacity, high power, long life, and strong stability. It is particularly suitable for outdoor camping, outdoor live broadcasting, outdoor construction, location shooting, home emergency power use and other scenes with high power consumption.

[0003] A very practical feature of outdoor power supplies is the ability to store power outdoors, and usually uses a compatible physical port to adapt to different types of charging power supplies. At present, the main ways to charge outdoor power supplies outdoors are solar panel charging (solar to DC charging) and vehicle battery charging. However, since the characteristics of solar panels and vehicle batteries are different, if solar panels are connected, the maximum power point tracking (MPPT) algorithm needs to be used to track the maximum power point. Therefore, it is necessary to automatically determine the type of DC power supply connected and use the corresponding method to control their charging of outdoor power supplies.

[0004] The traditional method of determining the type of DC power source is to try to pull down the voltage of the DC power source. If the voltage can be pulled down to a predetermined threshold, the DC power source is determined to be a solar panel, otherwise it is determined to be a car battery. However, if the car battery is weak, the DC power source may be misjudged as a solar panel. Summary of the invention

[0005] Therefore, the object of the present invention is to overcome the defects of the above-mentioned prior art and provide a method for determining the type of a DC power supply, wherein the DC power supply is configured to be connected to an outdoor power supply to charge the outdoor power supply, and the method comprises the following steps:

[0006] Step 1: Obtain a first equivalent resistance and a second equivalent resistance of the DC power supply corresponding to two different equivalent load resistances of the outdoor power supply respectively;

[0007] Step 2: Calculate the ratio of the first equivalent resistance to the second equivalent resistance;

[0008] Step 3: If the ratio is within a predetermined threshold range, it is determined that the DC power source is a vehicle battery; otherwise, it is determined that the DC power source is a solar panel.

[0009] According to the judgment method of the present invention, preferably, in the step 1, the first output current, the first output voltage, the second output current and the second output voltage of the DC power supply corresponding to two different equivalent load resistances of the outdoor power supply are collected, and the first equivalent resistance and the second equivalent resistance are calculated based on the first output current, the first output voltage, the second output current and the second output voltage and the open circuit voltage of the DC power supply.

[0010] According to the judging method of the present invention, preferably, the first output voltage and the second output voltage are greater than half of the open circuit voltage and less than the open circuit voltage.

[0011] According to the judging method of the present invention, preferably, the first output voltage and the second output voltage are greater than three quarters of the open circuit voltage and less than the open circuit voltage.

[0012] According to the determination method of the present invention, preferably, the first output voltage and the second output voltage are greater than four fifths of the open circuit voltage and less than the open circuit voltage.

[0013] According to the determination method of the present invention, preferably, the predetermined threshold value ranges from 0.7 to 1.3.

[0014] According to the determination method of the present invention, preferably, the predetermined threshold value ranges from 0.8 to 1.2.

[0015] According to the determination method of the present invention, preferably, the predetermined threshold value ranges from 0.9 to 1.1.

[0016] According to the determination method of the present invention, preferably, the outdoor power supply includes a charging circuit, and the equivalent load resistance of the outdoor power supply is adjusted by changing the charging circuit.

[0017] According to the determination method of the present invention, preferably, the charging circuit is a DC / DC circuit.

[0018] Compared with the prior art, the direct current power supply determination method of the present invention is simple to operate and has high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The embodiments of the present invention are further described below with reference to the accompanying drawings, in which:

[0020] Figure 1 Shows the RV curves for batteries and solar panels;

[0021] Figure 2 An equivalent circuit diagram of a DC power supply is shown;

[0022] Figure 3is a structural block diagram of a device including a DC power supply 10 and an outdoor power supply 20 according to an embodiment of the present invention;

[0023] like Figure 4 is a flow chart of a method for determining a type of a DC power supply according to an embodiment of the present invention; and

[0024] Figure 5 and Figure 6 Screen shots of the solar simulator display at different output currents are shown. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail by specific embodiments in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0026] In order to distinguish the types of DC power sources, the inventors have studied the output characteristics of vehicle batteries and solar panels. Through the study, it is found that an important characteristic of vehicle batteries is that their equivalent internal resistance is basically stable, while the equivalent internal resistance of solar panels decreases with the increase of voltage. In particular, when the voltage approaches the open circuit voltage Voc, the equivalent internal resistance of solar panels decreases sharply with the increase of voltage, see Figure 1 The RV curves of batteries and solar panels are shown in Figure 1. Therefore, by monitoring the equivalent internal resistance of the DC power supply, the type of DC power supply can be determined.

[0027] See also Figure 2 The equivalent circuit diagram of the DC power supply is shown in Figure 1. The model consists of an ideal voltage source (the voltage V OC Equivalent to open circuit voltage) and equivalent internal resistance R0. Figure 2 In, V bat Indicates the output voltage of the DC power supply, I bat Represents the output current of the DC power supply, R L Indicates the load resistance external to the DC power supply.

[0028] This model can simulate the static state of the DC power supply, that is, the output current I bat The voltage drop caused by the equivalent internal resistance R0. The output voltage of the DC power supply can be described by a simple equation:

[0029] V bat =I bat ·R L =V OC -R0·I bat (1)

[0030] That is: V OC =(R0+R L)·I bat (2)

[0031] By changing the load resistance R L To change the output current I of the DC power supply bat and output voltage V bat ,in:

[0032] When the output current and output voltage of the DC power supply are I1 and V1 respectively,

[0033]

[0034] When the output current and output voltage of the DC power supply are I2 and V2 respectively,

[0035]

[0036] Combining (3) and (4):

[0037] (R0+R L1 )·I1=(R0+R L2 )·I2

[0038] R0·I1+V1=R0·I2+V2

[0039] We can get:

[0040]

[0041] Based on formula (5), the equivalent resistance of the DC power supply can be obtained by collecting the output current and output voltage of the DC power supply, and then monitoring the change law of the equivalent resistance. Figure 1 , you can determine the type of DC power supply.

[0042] Therefore, an embodiment of the present invention provides a method for determining the type of a DC power supply, which determines the type of the DC power supply by sampling the equivalent resistance of the DC power supply and according to the change law of the equivalent resistance. Specifically, the output current and output voltage of the DC power supply at two value points are collected, the corresponding equivalent resistance is calculated according to Ohm's law, and the equivalent resistances of the two value points are compared. If the ratio of the two is near 1, for example, the ratio of the two is greater than 0.7 and less than 1.3, preferably greater than 0.8 and less than 1.2, and more preferably greater than 0.9 and less than 1.1, it indicates that the DC power supply is a vehicle-mounted battery, otherwise, it indicates that the DC power supply is a solar panel.

[0043] According to an embodiment of the present invention, the output voltage values ​​and corresponding current values ​​of two value points close to the opening voltage Voc are collected, especially, the value points are Preferably, the value point is between More preferably, the value point is between between.

[0044] According to an embodiment of the present invention, in order to improve accuracy, the voltage difference between the two value points is at least greater than 3% Voc, preferably greater than 5% Voc, and more preferably greater than 10% Voc.

[0045] See also Figure 3 The structure block diagram of the device including a DC power supply 10 and an outdoor power supply 20 according to an embodiment of the present invention is shown, and the outdoor power supply 20 is equivalent to a load connected to the DC power supply 10, wherein the outdoor power supply 20 includes a charging circuit 201 and an energy storage battery 202, and in particular, the charging circuit 201 includes a DC / DC converter. The DC power supply 10 charges the energy storage battery 202 through the charging circuit 201, and the energy storage battery 202 is configured to supply power to the power-consuming device through the output port O. In one embodiment of the present invention, the equivalent resistance R of the outdoor power supply is changed by changing the charging circuit 201. L In particular, the charging circuit includes a plurality of switching transistors, and the equivalent resistance R of the outdoor power source is changed by changing the switching logic of the plurality of switching transistors. L .

[0046] like Figure 4 The flowchart of the method for determining the type of a DC power supply according to an embodiment of the present invention includes the following steps:

[0047] Step S1: Obtain the open circuit voltage V of the DC power supply 10 OC The open circuit voltage Voc can be obtained from the manual of the DC power supply or by measurement. When the output voltage of the DC power supply 10 is the open circuit voltage Voc, the output current is 0;

[0048] Step S2: adjusting the output current of the DC power supply 10 to a first output current I1, for example, 0.5 A, and measuring a first output voltage V1 of the DC power supply 10;

[0049] Step S3: Calculate the first equivalent resistance value of the DC power supply

[0050] Step S4: adjusting the output current of the DC power supply 10 to a second output current I2, for example, 1.0 A, and measuring a second output voltage V2 of the DC power supply 10;

[0051] Step S5: Calculate the second equivalent resistance value of the DC power supply

[0052] Step S6: Calculate the ratio

[0053] Step S7: Ratio Compared with the predetermined threshold range, if For example The DC power source is determined to be the vehicle battery, otherwise it is determined to be the solar panel.

[0054] The inventors verified the effectiveness of the method of the embodiment of the present invention through specific experiments.

[0055] Chroma photovoltaic simulator is used as DC power source to charge outdoor power source. Figure 5 and Figure 6 The screenshot of the display screen of the solar simulator shown in the figure shows that the open circuit voltage of the DC power supply Voc=59.9V. The output current of the DC power supply is set to approximately 0.5A and 1.0A respectively. The corresponding DC power supply output voltage and DC power supply output current actually collected are: V1=56.408V, I1=0.5044A, V2=48.594V, I2=1.0081A respectively. The first equivalent resistance R1 and the second equivalent resistance R2 are calculated.

[0056]

[0057]

[0058] Then calculate the ratio

[0059] 0.446<0.7, so it is determined that the DC power source is a solar panel, which is consistent with the actual situation.

[0060] Then use the vehicle battery as a DC power source to charge the outdoor power source. The open circuit voltage Voc=47.65V is collected, and the output current of the DC power source is set to approximately 0.5A and 1.0A respectively. The corresponding DC power supply output voltage and DC power supply output current collected by the oscilloscope are: V1=47.41V, I1=0.501A, V2=47.14V, I2=1.002A, and the first equivalent resistance R1 and the second equivalent resistance R2 are calculated.

[0061]

[0062]

[0063] Then calculate the ratio

[0064] 0.7<0.89<1.3, so it is determined that the DC power source is the vehicle battery, which is consistent with the actual situation.

[0065] Although the present invention has been described through preferred embodiments, the present invention is not limited to the embodiments described herein but includes various changes and modifications that may be made without departing from the scope of the present invention.

Claims

1. A method for determining the type of a DC power supply, wherein: The DC power supply is configured to be connected to an outdoor power supply to charge the outdoor power supply, and the method comprises the following steps: Step 1: Obtain a first equivalent resistance and a second equivalent resistance of the DC power supply corresponding to two different equivalent load resistances of the outdoor power supply respectively; Step 2: Calculate the ratio of the first equivalent resistance to the second equivalent resistance; Step 3: If the ratio is within a predetermined threshold range, it is determined that the DC power source is a vehicle battery; otherwise, it is determined that the DC power source is a solar panel.

2. The determination method according to claim 1, wherein: In step 1, the first output current, the first output voltage, the second output current and the second output voltage of the DC power supply corresponding to two different equivalent load resistances of the outdoor power supply are collected, and the first equivalent resistance and the second equivalent resistance are calculated based on the first output current, the first output voltage, the second output current and the second output voltage and the open circuit voltage of the DC power supply.

3. The determination method according to claim 2, wherein: The first output voltage and the second output voltage are greater than half of the open circuit voltage and less than the open circuit voltage.

4. The determination method according to claim 2, wherein: The first output voltage and the second output voltage are greater than three quarters of the open circuit voltage and less than the open circuit voltage.

5. The determination method according to claim 2, wherein: The first output voltage and the second output voltage are greater than four fifths of the open circuit voltage and less than the open circuit voltage.

6. The determination method according to any one of claims 1 to 5, wherein: The predetermined threshold range is 0.7 to 1.

3.

7. The determination method according to any one of claims 1 to 5, wherein: The predetermined threshold value ranges from 0.8 to 1.

2.

8. The determination method according to any one of claims 1 to 5, wherein: The predetermined threshold value ranges from 0.9 to 1.

1.

9. The determination method according to any one of claims 1 to 5, wherein: The outdoor power supply includes a charging circuit, and the equivalent load resistance of the outdoor power supply is adjusted by changing the charging circuit.

10. The determination method according to claim 9, wherein: The charging circuit is a DC / DC circuit.

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